Tibial prosthesis with tibial bearing component securing feature

ABSTRACT

According to one example, a tibial prosthesis that can include a tibial bearing component, tibial baseplate, an insert and a fastener. The tibial bearing component can have medial and lateral proximal articular surfaces and an opposing distal surface. The tibial bearing component can define at least one recess therein with the recess having an opening at a periphery of the tibial bearing component. The tibial baseplate can be coupled to the tibial bearing component on the proximal surface thereof and having a distal surface configured to be disposed on a resected proximal surface of a tibia. The insert can be configured to be disposed within the recess and can engage the tibial baseplate and the tibial bearing component. The fastener can be insertable into the tibial bearing component and can be configured to retain the insert to the tibial baseplate.

CLAIM OF PRIORITY

This application is a continuation of U.S. patent application Ser. No.15/915,886, filed Mar. 8, 2018, which claims the benefit of U.S.Provisional Patent Application Ser. No. 62/469,924, filed on Mar. 10,2017, the benefit of priority of each of which is claimed hereby, andeach of which is incorporated by reference herein in its entirety.

FIELD

The present subject matter relates to orthopedic prostheses and, moreparticularly, to prostheses, systems and methods used in kneearthroplasties including revision knee arthroplasties.

BACKGROUND

Orthopedic procedures and prostheses are commonly utilized to repairand/or replace damaged bone and tissue in the human body. For example, aknee arthroplasty can be used to restore natural knee function byrepairing damaged or diseased articular surfaces of the femur and/ortibia. An incision is made into the knee joint to expose the bonescomprising the joint. Cut guides are used to guide the removal of thearticular surfaces that are to be replaced. Prostheses are used toreplicate the articular surfaces. Knee prostheses can include a femoralcomponent implanted on the distal end of the femur, which articulateswith a tibial bearing component and a tibial component implanted on theproximal end of a tibia to replicate the function of a healthy naturalknee. Various types of arthroplasties are known including a total kneearthroplasty, where all of the articulating compartments of the jointare repaired with prosthetic components.

OVERVIEW

This disclosure pertains generally to tibial prostheses, systems, andmethods for a knee arthroplasty including a revision knee arthroplasty,The present inventors have recognized, among other things, that a degreeof micro-motion experienced by a tibial bearing component relative to atibial baseplate can be reduced by providing an additional lockdownfeature(s). Reduction of micro-motion can provide better overalldurability for the tibial beating component when assembled with thetibial baseplate. Furthermore, present inventors have recognized thatwith additional lockdown features, a greater rigidity and torsionalstrength can be provided to the tibial bearing component. As such, metalreinforcement need not be provided to a spine of the tibial bearingcomponent. Thus, the weight of the tibial bearing component can bereduced.

As used herein, “micro-motion” refers to the small motions that mayexist between prosthesis components, such as between the tibialbaseplate and the tibial bearing component, respectively, uponapplication of force. Such small motions may occur as a result ofmaterial deformation in one or both of the interacting components, ormay result from slight spaces or clearances therebetween, for example.Micro-motion is distinguished from “mobile bearing” applications, whichexperience relatively larger motions as the tibial bearing componentarticulates with respect to the tibial baseplate (such as by sliding orrotating) along a desired motion path.

As used herein, a “fixed bearing” tibial prosthesis is a prosthesis inwhich the tibial bearing component is seated atop the tibial baseplatein a final, locked, and secured position. In this secured position,lift-off of the tibial bearing component from the tibial baseplate aswell as transverse movement of the tibial bearing component relative tothe tibial baseplate is prevented during natural articulation of theknee. Some micro-motion may exist between the tibial bearing componentand tibial baseplate in a fixed bearing prosthesis.

To further illustrate the apparatuses and systems disclosed herein, thefollowing non-limiting examples are provided:

Example 1 is a tibial prosthesis for a knee arthroplasty that canoptionally comprise: a tibial bearing component having medial andlateral proximal articular surfaces and an opposing distal surface,wherein the tibial bearing component defines at least one recess thereinwith the recess having an opening at a periphery of the tibial bearingcomponent; a tibial baseplate coupled to the tibial beating component ona proximal surface thereof and having a distal surface configured to bedisposed on a resected proximal surface of a tibia; an insert configuredto be disposed within the recess and engage the tibial baseplate and thetibial bearing component; and a fastener retaining the insert to thetibial baseplate.

In Example 2, the subject matter of Example 1 can optionally includewherein the tibial bearing component comprises a posterior-stabilizedtibial bearing component with a spine disposed between the medial andlateral proximal articular surfaces.

in Example 3, the subject matter of any one or more of Examples 1-2 canoptionally include wherein the insert comprises: a body having anaperture defined thereby, the aperture receives a head of the fastener;a first foot connected to the body and extending distal therefrom, thefirst foot having a first side surface engaging the tibial baseplate;and a second foot connected to the body and extending distal therefrom,the second foot spaced from the first foot and having a second sidesurface engaging the tibial baseplate.

In Example 4, the subject matter of Example 3 can optionally includewherein the insert further comprises a tab extending proximally from thebody, the tab engaging the tibial bearing component to retain the insertwithin the tibial bearing component.

In Example 5, the subject matter of any one or more of Examples 3-4 canoptionally include wherein the body includes a first wing that extendslateral of the first foot and a second wing that extends medial of thesecond foot.

in Example 6, the subject matter of any one or more of Examples 3-5 canoptionally include wherein the head of the fastener and the apertureshare a similar curvature such the fastener is self-centering within theinsert.

In Example 7, the subject matter of any one or more of Examples 1-6 canoptionally include wherein the opening is at an anterior portion of theperiphery of the tibial bearing component and the insert is disposed inthe recess such that substantially an entirety of the insert is disposedanterior of the fastener.

In Example 8, the subject matter of any one or more of Examples 1-7 canoptionally include wherein the tibial baseplate includes a railextending from the proximal surface along a periphery thereof, whereinthe rail has a gap in a region of the recess, and wherein with theinsert disposed in the recess, at least a portion thereof extends intothe gap and engages the rail to limit micro-motion of the tibial bearingcomponent.

In Example 9, the subject matter of any one or more of Examples 1-8 canoptionally include a second aperture formed in the tibial bearingcomponent and extending from between the medial and lateral proximalarticular surfaces to communicate with the recess, wherein the secondaperture is configured to receive at least a portion of the fastener,and wherein the second aperture is angled relative to a proximal-distalaxis of the tibial bearing component such that second aperture extendsboth proximal-distal and anterior-posterior.

Example 10 is a system for use in a knee arthroplasty can optionallycomprise: a tibial bearing component having medial and lateral proximalarticular surfaces and an opposing distal surface, wherein the tibialbearing component defines at least one recess therein with the recesshaving an opening at a periphery of the tibial bearing component; atibial baseplate configured to receive the tibial bearing component on aproximal surface thereof and having a distal surface configured to bedisposed on a resected proximal surface of a tibia; an insert disposablethrough the opening and into the recess, the insert configure to engagethe tibial baseplate and the tibial bearing component when the insert,the tibial baseplate and the tibial bearing component are assembledtogether; and a fastener insertable into the tibial bearing componentand configured to retain the insert to the tibial baseplate.

In Example 11, the subject matter of Example 10 can optionally includewherein the tibial bearing component comprises a posterior-stabilizedtibial bearing component with a spine disposed between the medial andlateral proximal articular surfaces, and wherein the fastener isinsertable into an anterior portion of the spine.

In Example 12, the subject matter of any one or more of Examples 10-11can optionally include wherein the insert comprises: a body having anaperture defined thereby, the aperture configured to receive a head ofthe fastener, a first foot extending generally distal from the body andhaving a first side surface engaging the tibial baseplate; and a secondfoot extending generally distal from the body and spaced from the firstfoot, the second foot having a second side surface engaging the tibialbaseplate.

In Example 13, the subject matter of Example 12 can optionally includewherein the insert further comprises a tab extending proximally from thebody and configured to engage the tibial bearing component to retain theinsert within the tibial bearing component.

In Example 14, the subject matter of any one or more of Examples 12-13can optionally include wherein the body includes a first wing thatextends lateral of the first foot and a second wing that extends medialof the second foot.

In Example 15, the subject matter of any one or more of Examples 12-14can optionally include wherein the head of the fastener and the apertureshare a similar curvature such the fastener is self-centering within theinsert.

In Example 16, the subject matter of any one or more of Examples 10-15can optionally include wherein the opening is at an anterior portion ofthe periphery of the tibial bearing component and the insert is disposedin the recess when assembled such that substantially an entirety of theinsert is disposed anterior of the fastener.

In Example 17, the subject matter of any one or more of Examples 10-16can optionally include wherein the tibial baseplate includes a railextending from the proximal surface along a periphery thereof, whereinthe rail has a gap in a region of the recess and forms a part of theopening, and wherein with the insert disposed in the gap the insert isconfigured to engage the rail to limit micro-motion of the tibialbearing component.

In Example 18, the subject matter of any one or more of Examples 10-17can optionally include a second aperture formed in the tibial bearingcomponent and extending from the medial and lateral proximal articularsurfaces to communicate with the recess, wherein the second aperture isconfigured to receive at least a portion of the fastener, and whereinthe second aperture is angled relative to a proximal-distal axis of thetibial bearing component such that second aperture extends bothproximal-distal and anterior-posterior.

Example 19 is a method of assembling a tibial prosthesis for a kneearthroplasty, the method can optionally comprise: passing an insertthrough a peripheral opening and into a recess formed in a tibialbearing component; engaging a portion of the insert with the tibialbearing component while having wings of the insert received incorresponding grooves that are part of the recess; engaging the tibialbearing component with a tibial baseplate; and fastening the insert tothe tibial baseplate.

In Example 20, the subject matter of Example 19 can optionally includewherein fastening the insert to the tibial baseplate includes passing afastener through a proximal surface region located between medial andlateral proximal articular surfaces of the tibial bearing component.

In Example 21, the subject matter of any one or more of Examples 19-20can optionally include engaging a first foot of the insert with a firstportion of a rail of the tibial baseplate and engaging a second foot ofthe insert with a second portion of the rail of the tibial baseplate.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralscan describe similar components in different views. Like numerals havingdifferent letter suffixes can represent different instances of similarcomponents. The drawings illustrate generally, by way of example, butnot by way of limitation, various examples discussed in the presentdocument.

FIG. 1A shows a perspective view of a prosthesis assembly including afemoral component, tibial bearing component and tibial baseplateaccording to an example of the present application.

FIG. 1B show a cross-sectional view of the prosthesis assembly of FIG.1A showing an insert and a fastener in addition to the aforementionedfemoral component, tibial bearing component and tibial baseplateaccording to an example of the present application.

FIG. 2 shows a cross-sectional view of another example of the prosthesisassembly but with the femoral component moved to an extension positionrather than the 135° flexion position previously illustrated accordingto an example of the present application.

FIGS. 3A-3D illustrate a method of assembly for a tibial prosthesisaccording to an example of the present application.

FIG. 4 shows the tibial prosthesis after having undergone the assemblypreviously illustrated in FIG. 3.

FIG. 4A shows an enlargement of a portion of the tibial prosthesisfurther illustrating the insert engaging portions of the tibialbaseplate according to an example of the present application.

FIG. 5 show a perspective view of the insert according to an example ofthe present application.

FIG. 5A shows a plan view of a distal portion of insert including firstand second feet and an aperture according to an example of the presentapplication.

FIG. 5B is a cross-sectional view of the insert along line 5B-5B of FIG.5A.

FIG. 6 is a plan view of the fastener according to an example of thepresent application.

FIGS. 7-7C show the tibial bearing component from various perspectivesaccording to an example of the present application.

FIGS. 8A and 8B show the tibial baseplate from various perspectivesaccording to an example of the present application.

DETAIL ED DESCRIPTION

The present application relates tibial prostheses, systems, and methods.The systems, for example, can include a tibial bearing component, atibial baseplate, an insert and a fastener.

The present application relates a prosthesis assembly that can be usedin a knee arthroplasty and/or as part of a later knee revision surgery.As described herein, the prosthesis assembly can include tibialprosthesis and a femoral prosthesis. This application focuses on aspectsof the tibial prosthesis, which can include a tibial baseplate, a tibialbearing component, an insert and a fastener. As discussed previously,the tibial prosthesis can be configured to reduce micro-motion betweenthe tibial bearing component and the tibial baseplate. This can improvethe durability of the tibial prosthesis. Additional features andbenefits of the various examples provided herein will be discussedand/or will be apparent to one of ordinary skill in the art.

As used herein, the terms “proximal” and “distal” should be given theirgenerally understood anatomical interpretation. The term “proximal”refers to a direction generally toward the torso of a patient, and“distal” refers to the opposite direction of proximal, i.e., away fromthe torso of a patient. It should be understood that the use of theterms “proximal” and “distal” should be interpreted as though thepatient were standing with the knee joint in extension despite theapparatuses described herein generally being used with the knee joint inflexion. The intent is to differentiate the terms “proximal” and“distal” from the terms “anterior” and “posterior”. As used herein, theterms “anterior” and “posterior” should be given their generallyunderstood anatomical interpretation. Thus, “posterior” refers to a rearof the patient, e.g., a back of the knee. Similarly, “anterior” refersto a front of the patient, e.g., a front of the knee. Thus, “posterior”refers to the opposite direction of “anterior”, Similarly, the term“lateral” refers to the opposite direction of “medial”.

FIGS. 1A and 1B illustrate a prosthesis assembly 10 that can include afemoral prosthesis 12 and a tibial prosthesis 14. In the example of FIG.1A, the prosthesis assembly 10 is shown in a perspective view with thefemoral prosthesis 12 articulated relative to the tibial prosthesis 14to 135° of flexion. FIG. 1B shows the prosthesis assembly 10 in across-sectional view along a sagittal plane. The sagittal plane extendsalong the anterior-posterior direction and the proximal-distal directionof the prosthesis assembly 10.

According to the examples provided herein, the prosthesis assembly 10can comprise a posterior stabilized (PS) prosthesis. Thus, the tibialprosthesis can include a spine 16 and the femoral prosthesis 12 caninclude a cam 18 (FIG. 1B). The spine 16 and the cam 18 can designed tocooperate with one another to stabilize femoral prosthesis 12 withrespect to tibial prosthesis 14 in lieu of a posterior cruciate ligament(PCL). However, other prosthesis designs are contemplated including amid-level constraint (MLC) design, a cruciate retaining (CR) design, andan ultra-congruent (UC) design, for example. The CR and UC designs omitthe spine 16 and cam 18, such that femoral prosthesis 12 defines anintercondylar space between medial and lateral condyles 20 and 22 (onlyone shown in FIG. 1B) that is entirely open and uninterrupted by the cam18. CR tibial prostheses are generally used in surgical procedures whichretain the PCL.

Turning to the components illustrated in FIG. 1A and/or FIG. 1B, thetibial prosthesis 14 can include a tibial bearing component 26, a tibialbaseplate 24, an insert 28, and a fastener 30 (FIG. 1B). The tibialbearing component 26 can include the spine 16, a proximal medialarticular surface 32 and a proximal lateral articular surface 34. Thetibial baseplate 24 can include a keel 36. Additional components such asa stem 38 can be used with the prosthesis assembly 10 in some examples.

As shown in FIGS. 1A and 1B, the femoral prosthesis 12 can be disposedatop and can articulate relative to the tibial prosthesis 14. Sucharticulation can be between the medial and lateral condyles 20 and 22and the proximal medial articular surface 32 and the proximal lateralarticular surface 34, respectively. The proximal medial articularsurface 32 and the proximal lateral articular surface 34 can be shaped(e.g., curved) to facilitate such articulation during knee jointflexion. The spine 16 of the tibial bearing component 26 can becentrally located between the proximal medial articular surface 32 andthe proximal lateral articular surface 34 as shown in FIG. 1A. The spine16 can be configured to engage with the cam 18 during flexion as shownin FIG. 1B. Such engagement provides additional stability that wouldotherwise be offered by ligaments such as the PCL.

The tibial bearing component 26 can be secured to the tibial baseplate24 as shown in FIGS. 1A and 1B. Such securement can be facilitated bythe use of rails, notches, bosses and other features that will bedescribed subsequently. Additionally, as shown in FIG. 1B, the insert 28and the fastener 30 can be used to further secure the tibial beatingcomponent 26 to the tibial baseplate 24 as will be describedsubsequently.

As shown in FIG. 1B, the insert 28 can be disposed within a recess 40 ofthe tibial bearing component 26 atop a proximal surface 42 of the tibialbaseplate 24 when assembled. The fastener 30 can extend at leastpartially through an aperture 44 into the recess 40 and can engage theinsert 28 along a head portion thereof. The fastener 30 can additionallyextend to fasten to the tibial baseplate 24 along a threaded portion asillustrated and described subsequently. As will be further discussedsubsequently, features of the insert 28, fastener 30, tibial baseplate24 and tibial bearing component 26 reduce micro-motion of the tibialbearing component 26 relative to the tibial baseplate 24.

In addition to the proximal surface 42, the tibial baseplate 24 has adistal surface 46 configured to interface with and abut a resectedsurface of the tibia (not shown). The keel 36 extends generally distalof the distal surface 46 according to the example of FIGS. 1A and 1B.The keel 36 can be configured to be received in a corresponding recesswithin the tibia to facilitate fixation of the tibial baseplate 24 tothe tibia. However, according to other examples the tibial baseplate 24can use additional or other features (i.e. features additional to orother than the keel 36) to facilitate fixation to the tibia includingbone cement, spikes, augments and/or pegs. Thus, the keel 36 and stem 38need not be utilized in all examples.

FIG. 2 shows a second example of a prosthesis assembly 110 of similarconstruction to the prosthesis assembly 10 of FIGS. 1A and 1B. However,in FIG. 2 the location of the aperture 144 has been altered relative tothe aperture 44. The aperture 144 does not pass through the spine 116 inthe embodiment of FIG. 2 but is disposed anterior thereof. In contrast,the aperture 44 passed through an anterior portion of the spine 16 asshown in FIGS. 1A and 1B. Thus, it is contemplated that the aperture 44,144 can be disposed in a plurality of positions including passingthrough at least a portion of the spine, anterior of the spine orposterior of the spine.

FIG. 2 additionally shows the femoral prosthesis 12 articulated to anextension position relative to the tibial prosthesis 14. In suchposition, the cam 18 can be disposed out of contact with the spine 116.

Thus, as shown in one or more of FIGS. 1A, 1B and 2, the tibial bearingcomponent 26 can have medial and lateral proximal articular surfaces 32,34 (FIG. 1A) and an opposing distal surface 35 (FIG. 2). The tibialbearing component 26 can define at least one recess 40 therein with therecess 40 having an opening at a periphery of the tibial bearingcomponent 26. The tibial baseplate 24 can be coupled to the tibialbearing component 26 on the proximal surface 42 thereof and having adistal surface 45 configured to be disposed on a resected proximalsurface of a tibia. The insert 28 can be configured to be disposedwithin the recess 40 and can engage the tibial baseplate 24 and thetibial bearing component 26. The fastener 30 can be insertable into thetibial bearing component 26 and can be configured to retain the insert28 to the tibial baseplate 24.

FIGS. 3A-3D illustrate a method 200 by which the tibial prosthesis 14can be assembled. The method 200 includes passing the insert 28 througha peripheral opening 202 and into the recess 40 formed in the tibialbearing component 26 as shown in FIGS. 3A and 3B. The method engages aportion (e.g., tab 306 in FIG. 5) of the insert 28 with the tibialbearing component 26 while having first and second wings (described andnumber subsequently in reference to FIGS. 4A-5B) of the insert 28received in corresponding grooves (described and number subsequently inreference to FIG. 4A) that are part of the recess 40. A tool can be usedin some instances to facilitate passing the insert 28 and engagement asdescribed above. The tool can also facilitate removal of the insert 28from the recess 40 in some examples.

The method 200 can engage the tibial bearing component 26 with thetibial baseplate 24 as shown in FIG. 3C. This can initially beaccomplished with engagement features such as dovetail boss, rails,notches or the like as will be illustrated and described subsequently.The insert 28 can be fastened to the tibial baseplate 24 as is initiallydemonstrated in FIG. 3D by passing the fastener 30 through the aperture144 and into the recess 40 to engage the insert 28. The fastener 30 canthen be rotated to thread with the tibial baseplate 24 to secure theinsert 28 to the tibial baseplate 24 and thereby secure the tibialbearing component 26 to the tibial baseplate 24.

As will be discussed and illustrated in reference to further FIGURESsubsequently, fastening the insert 28 to the tibial baseplate 24 caninclude passing the fastener 40 through a region located between medialand lateral proximal articular surfaces 32, 34 of the tibial bearingcomponent 26 (the location of the aperture 144) as shown in FIG. 3D. Themethod 200 can also engage a first foot of the insert with a firstportion of a rail of the tibial baseplate and can engage a second footof the insert with a second portion of the rail of the tibial baseplateas will be discussed subsequently in reference to FIGS. 4 and 4A.

FIG. 4 shows the assembled tibial prosthesis 14. FIG. 4A is an enlargedview of an anterior portion of the tibial baseplate 24, the tibialbearing component 26 and the insert 28.

As is best shown in FIG. 4A, the insert 28 can be positioned in therecess 40 and can be configured to engage portions of the tibialbaseplate 24. More particularly, the insert 28 can include a body 302, afirst foot 304A and a second foot 304B as shown in FIGS. 4A, 5 and 5A. Atab 306 can project proximal of the body 302 as shown in FIGS. 5 and 5B.The body 302 can include first and second wings 308A and 308B thatextend outward of the first foot 304A and second foot 304B,respectively. According to one example, the first wing 308A extendslateral of the first foot 304A and the second wing 308B extends medialof the second foot 304B.

As shown in FIGS. 4 and 4A, the opening 202 can be located at ananterior portion 204 of a periphery 206 of the tibial bearing component26. The insert 28 can be disposed in the recess 40 such thatsubstantially an entirety or all of the insert 28 is disposed therein.Additionally, when disposed in the recess 40, substantially an entiretyof the insert 28 can be disposed anterior of the fastener 30 (FIGS. 1Band 2).

As shown in FIG. 4A, the tibial baseplate 24 can include a rail 208extending from the proximal surface 42 along the periphery 206. The rail208 has a gap 210. The gap 210 can be part of the opening 202, andtherefore, can comprise part of the recess 40. In some examples, part ofthe rail 208 and gap 210 can be disposed anterior of the recess 40 andopening 202. The example of FIG. 4A illustrates that with the insert 28disposed in the recess 40, at least a portion of the insert 28 extendsinto the gap 210 and engages the rail 208 (e.g. along the medial andlateral side surfaces of the first foot 304A and second foot 304B asshown subsequently in FIGS. 5 and 5A). Such engagement, along withengagement of the insert 28 against the proximal surface 42, can limitmicro-motion of the tibial bearing component 26 relative to the tibialbaseplate 24 with securement of the fastener 30.

As shown in FIG. 4A, the first and second wings 308A and 308B areconfigured to be received in corresponding grooves 312A and 312B thatare part of the recess 40. The grooves 312A and 212B are shaped similarto the wings 308A and 308B. The wings 308A and 308B can be disposed onand engage projections 314A, 314B that form a distal portion of thegrooves 312A and 312B.

Turning to FIGS. 5-5B, the body 302 can have an aperture 320 definedthereby. The aperture 320 can be configured to receive a head of thefastener 30 as was previously illustrated in FIGS. 1B and 2. Moreparticularly, according to some examples the aperture 320 can behemispherical in shape along a portion thereof so as to facilitatecentering of the fastener 30 during insertion. The hemispherical shapecan also minimize stretch loss of the fastener 30 due to settling of thefastener 30 during use. In some examples, such as that of FIG. 5B, anaxis A of the aperture 320 can be angled relative to a proximal-distalaxis PDA of the insert 28. This causes the fastener 30 to be angled in adirection in addition to the proximal-distal direction such as theanterior-posterior direction.

The first foot 304A can be connected to the body 302 and can extenddistal therefrom in a direction generally perpendicular to that of wing308A. As shown in FIG. 5A, in addition to a distal surface 322A, thefirst foot 304A can have a lateral side surface 324A engaging the tibialbaseplate 24 when assembled as illustrated and described above inreference to FIG. 4A. Similarly, the second foot 304B can be connectedto the body 302 and can extend distal therefrom. The second foot 304Bcan be spaced from the first foot 304A. The second foot 304B can have adistal surface 322B and can have a medial side surface 324B engaging thetibial baseplate 24 when assembled as illustrated and described above inreference to FIG. 4A.

The tab 306 can extend proximally from the body 304 and can engage thetibial bearing component 26 to temporarily retain the insert 28 withinthe tibial bearing component 26 such as illustrated in FIG. 3B of themethod 200. More particularly, the tab 306 has an anterior face 307(FIG. 5B) that engages a corresponding surface of the tibial bearingcomponent 26 so as not to allow the insert 28 to be withdrawn from therecess 40 such as in the posterior-to-anterior direction (an opposingdirection to the direction of insertion of the insert 28 into the recess40 as shown in FIG. 3A).

FIG. 6 shows an example of the fastener 30 in greater detail. Thefastener 30 can have a head portion 402 and a threaded portion 404. FIG.6 provides an enlargement of the threaded portion 404. As discussed withregard to the insert 28 of FIGS. 5-5B, the head portion 402 can share asa similar curvature as the aperture 320. For example, the head portion402 can be provided with a hemispherical configuration similar to thatof the aperture 320 so as to facilitate centering of the screw duringinsertion (e.g. the conformity of the hemispherical head and the insertcan be anywhere between a 1:1 and a 1:1.2 ratio, inclusive). Suchconfiguration can also minimize stretch loss due to the fastenersettling. A neck region 406 between the head portion 402 and the threadportion can have a necked down area with a diameter smaller than a minordiameter of the threaded portion 404. This can prevent notching of theneck region 406 during fabrication.

As shown in FIG. 6, the threaded portion 404 can include rounded rootradii and the minor diameter can be relative to a major diameter toimprove the strength of the fastener relative to that of a standardthread.

FIGS. 7-7C show a tibial bearing component 526 similar in constructionto that of tibial bearing component 26 save that the disposition of anaperture 544 such so as to extend through at least an anterior portionof the spine 16. Thus, an anterior portion 502 of the spine 16 has acut-out 504 as shown in FIG. 7. All other features of the tibial bearingcomponent 526 are similar to or identical to those of the tibial bearingcomponent 26 as previously described.

As shown in FIG. 7A, the spine 16 can be centrally located between themedial articular surface 32 and the lateral articular surface 34. Aposterior region 506 of the spine 16 can have a radius such that theposterior region 506 is convexly shaped in a medial-lateral directionwhen viewed in a transverse plane. In contrast, the anterior portion 502can be substantially flat when viewed in the transverse plane.

FIG. 7B shows a plan view of the distal surface 35 of the tibial bearingcomponent 526. FIG. 7B additionally shows the recess 40. It should benoted that although the recess 40 and corresponding insert 28 are shownpositioned at the anterior region and extending to an anterior peripheryof the tibial bearing component 26 and the tibial baseplate 24 in theexamples provided, in other embodiments the recess 40 and insert 28 canbe disposed in other locations of the tibial bearing component 26 andthe tibial baseplate 24. Additionally, although a substantiallyanterior-posterior insertion direction for the insert 28 into the recess40 was illustrated and described, in other examples the insertiondirection can be in another direction (e.g., medial-lateral,proximal-distal) or combinations of directions (e.g., medial-lateral andanterior-posterior).

FIG. 7B also illustrates additional connection mechanisms such as adouble dovetail notch 508 and peripheral notches 510A and 510B thesefeatures are configured to attach to a double dovetail boss 512 andundercut rails 514A, 514B, respectively of the tibial baseplate 24 asshown in FIG. 8A. Upon assembly, the tibial bearing component 26, 126,526 can be advanced along a path, such that tibial bearing component 26,126, 526 moves along a generally anterior-to-posterior path as thedouble dovetail notch 508 begins to engage with the double dovetail boss512 and the peripheral notches 510A and 510B begin to engage with theundercut rails 514A, 514B. Further posterior movement of the tibialbearing component 212 causes a tight interfitting engagement betweenthese features. As is discussed and illustrated further in reference toFIG. 3, further engagement and securement of the tibial bearingcomponent 26, 126 526 to the tibial baseplate 24 is facilitated by theinsert 28 and the fastener 30.

As was previously shown in reference to FIGS. 1B and 2, the aperture 44,144, 544 can be configured to receive at least a portion of the fastener30 (FIGS. 1B and 2) therein. Indeed, upon assembly a head portion of thefastener 30 may remain in the aperture 44, 144, 544. According to theexample of FIG. 7C, the aperture 544 can be angled (along axis B)relative to a proximal-distal axis (not shown) of the tibial bearingcomponent 526 such that the aperture 544 extends both proximal-distaland anterior-posterior. The angle can be in a manner similar oridentical to that provided for the aperture 320 of the insert 28 aspreviously discussed. In other examples, the aperture and/or aperture ofthe insert 28 can be angled in any manner desired not just in theproximal-distal and anterior-posterior manner illustrated.

FIGS. 7B and 7C illustrate the recess 40 in further detail including thegrooves 312A and 312B (FIG. 7B). FIGS. 7B and 7C also show a notch 516that can form a part of the recess 40. The notch 516 can be positionedanterior of the aperture 544 along a proximal portion of the recess 40.The notch 516 is configured to receive the tab 306 (FIGS. 5 and 5B) whenthe insert 28 is received in the recess 40. An anterior surface 518 thatforms a part of the notch 516 is configured to engage the anterior face307 (FIG. 5B) of the insert 28. This engagement can temporarily restrictmovement of the insert 28 such that the insert cannot easily bewithdrawn from the recess 40 such as in the posterior-to-anteriordirection (an opposing direction to the direction of insertion of theinsert 28 into the recess 40 as shown in FIG. 3A).

FIGS. 8A and 8B show the tibial baseplate 24. In particular, FIG. 8Ashows the proximal surface 42 of the tibial baseplate 24. FIG. 8B showsa plan view of a proximal portion of the tibial baseplate 24. Additionalfeatures shown include the rail 208 extending from the proximal surface42 along the periphery 206. The rail 208 has the gap 210 as previouslydiscussed in reference to FIG. 4A. The gap 210 can be part of theopening 202, and therefore, can comprise part of the recess 40. As shownin FIG. 8A, the tibial baseplate 24 can also include the double dovetailboss 512 and the undercut rails 514A, 514B as previously discussed.

Additional Notes

The above detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific embodiments in which theinvention can be practiced. These embodiments are also referred toherein as “examples.” Such examples can include elements in addition tothose shown or described. However, the present inventors alsocontemplate examples in which only those elements shown or described areprovided. Moreover, the present inventors also contemplate examplesusing any combination or permutation of those elements shown ordescribed (or one or more aspects thereof), either with respect to aparticular example (or one or more aspects thereof), or with respect toother examples (or one or more aspects thereof) shown or describedherein.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In this document, the terms “including” and “inwhich” are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, device,article, composition, formulation, or process that includes elements inaddition to those listed after such a term in a claim are still deemedto fall within the scope of that claim. Moreover, in the followingclaims, the terms “first,” “second,” and “third,” etc. are used merelyas labels, and are not intended to impose numerical requirements ontheir objects.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) can be used in combination with each other. Otherexamples can be used, such as by one of ordinary skill in the art uponreviewing the above description. The Abstract is provided to comply with37 CFR. § 1.72(b), to allow the reader to quickly ascertain the natureof the technical disclosure. It is submitted with the understanding thatit will not be used to interpret or limit the scope or meaning of theclaims. Also, in the above detailed description, various features can begrouped together to streamline the disclosure. This should not beinterpreted as intending that an unclaimed disclosed feature isessential to any claim. Rather, inventive subject matter can lie in lessthan all features of a particular disclosed example. Thus, the followingclaims are hereby incorporated into the detailed description as examplesor embodiments, with each claim standing on its own as a separateexample, and it is contemplated that such examples can be combined witheach other in various combinations or permutations. The scope of theinvention should be determined with reference to the appended claims,along with the full scope of equivalents to which such claims areentitled.

The claimed invention is:
 1. A tibial prosthesis for a knee arthroplastycomprising: a tibial bearing component having medial and lateralproximal articular surfaces and an opposing distal surface, wherein thetibial bearing component defines at least one recess therein with therecess having an opening at a periphery of the tibial bearing component;a tibial baseplate coupled to the tibial bearing component on a proximalsurface thereof and having a distal surface configured to be disposed ona resected proximal surface of a tibia; an insert configured to bedisposed within the recess and engage the tibial baseplate and thetibial bearing component; and a fastener retaining the insert to thetibial baseplate.
 2. The tibial prosthesis of claim 1, wherein thetibial bearing component comprises a posterior-stabilized tibial bearingcomponent with a spine disposed between the medial and lateral proximalarticular surfaces.
 3. The tibial prosthesis of claim 1, wherein theinsert comprises: a body having an aperture defined thereby, theaperture receives a head of the fastener; a first foot connected to thebody and extending distal therefrom, the first foot having a first sidesurface engaging the tibial baseplate; and a second foot connected tothe body and extending distal therefrom, the second foot spaced from thefirst foot and having a second side surface engaging the tibialbaseplate.
 4. The tibial prosthesis of claim 3, wherein the insertfurther comprises a tab extending proximally from the body, the tabengaging the tibial bearing component to retain the insert within thetibial bearing component.
 5. The tibial prosthesis of claim 3, whereinthe body includes a first wing that extends lateral of the first footand a second wing that extends medial of the second foot.
 6. The tibialprosthesis of claim 3, wherein the head of the fastener and the apertureshare a similar curvature such the fastener is self-centering within theinsert.
 7. The tibial prosthesis of claim 1, wherein the opening is atan anterior portion of the periphery of the tibial bearing component andthe insert is disposed in the recess such that substantially an entiretyof the insert is disposed anterior of the fastener.
 8. The tibialprosthesis of claim 1, wherein the tibial baseplate includes a railextending from the proximal surface along a periphery thereof, whereinthe rail has a gap in a region of the recess, and wherein with theinsert disposed in the recess, at least a portion thereof extends intothe gap and engages the rail to limit micro-motion of the tibial bearingcomponent.
 9. The tibial prosthesis of claim 1, further comprising asecond aperture formed in the tibial bearing component and extendingfrom between the medial and lateral proximal articular surfaces tocommunicate with the recess, wherein the second aperture is configuredto receive at least a portion of the fastener, and wherein the secondaperture is angled relative to a proximal-distal axis of the tibialbearing component such that second aperture extends both proximal-distaland anterior-posterior.
 10. A system for use in a knee arthroplastycomprising: a tibial bearing component having medial and lateralproximal articular surfaces and an opposing distal surface, wherein thetibial bearing component defines at least one recess therein with therecess having an opening at a periphery of the tibial bearing component;a tibial baseplate configured to receive the tibial bearing component ona proximal surface thereof and having a distal surface configured to bedisposed on a resected proximal surface of a tibia; an insert disposablethrough the opening and into the recess, the insert configure to engagethe tibial baseplate and the tibial bearing component when the insert,the tibial baseplate and the tibial bearing component are assembledtogether; and a fastener insertable into the tibial bearing componentand configured to retain the insert to the tibial baseplate.
 11. Thesystem of claim 10, wherein the tibial bearing component comprises aposterior-stabilized tibial bearing component with a spine disposedbetween the medial and lateral proximal articular surfaces, and whereinthe fastener is insertable into an anterior portion of the spine. 12.The system of claim 10, wherein the insert comprises: a body having anaperture defined thereby, the aperture configured to receive a head ofthe fastener; a first foot extending generally distal from the body andhaving a first side surface engaging the tibial baseplate; and a secondfoot extending generally distal from the body and spaced from the firstfoot, the second foot having a second side surface engaging the tibialbaseplate.
 13. The system of claim 12, wherein the insert furthercomprises a tab extending proximally from the body and configured toengage the tibial bearing component to retain the insert within thetibial bearing component.
 14. The system of claim 12, wherein the bodyincludes a first wing that extends lateral of the first foot and asecond wing that extends medial of the second foot.
 15. The system ofclaim 12, wherein the head of the fastener and the aperture share asimilar curvature such the fastener is self-centering within the insert.16. The system of claim 10, wherein the opening is at an anteriorportion of the periphery of the tibial bearing component and the insertis disposed in the recess when assembled such that substantially anentirety of the insert is disposed anterior of the fastener.
 17. Thesystem of claim 10, wherein the tibial baseplate includes a railextending from the proximal surface along a periphery thereof, whereinthe rail has a gap in a region of the recess and forms a part of theopening, and wherein with the insert disposed in the gap the insert isconfigured to engage the rail to limit micro-motion of the tibialbearing component.
 18. The system of claim 10, further comprising asecond aperture formed in the tibial bearing component and extendingfrom the medial and lateral proximal articular surfaces to communicatewith the recess, wherein the second aperture is configured to receive atleast a portion of the fastener, and wherein the second aperture isangled relative to a proximal-distal axis of the tibial bearingcomponent such that second aperture extends both proximal-distal andanterior-posterior.
 19. A method of assembling a tibial prosthesis for aknee arthroplasty, the method comprising: passing an insert through aperipheral opening and into a recess formed in a tibial bearingcomponent; engaging a portion of the insert with the tibial bearingcomponent while having wings of the insert received in correspondinggrooves that are part of the recess; engaging the tibial bearingcomponent with a tibial baseplate; and fastening the insert to thetibial baseplate.
 20. The method of claim 19, wherein fastening theinsert to the tibial baseplate includes passing a fastener through aproximal surface region located between medial and lateral proximalarticular surfaces of the tibial bearing component.